The background description provided herein is solely for the purpose of generally presenting the context of the illustrative embodiments of the disclosure. Aspects of the background description are neither expressly nor impliedly admitted as prior art against the claimed subject matter.
Polymers, both organic and inorganic, have been utilized for more than 30 years in different flooding strategies adapted to facilitate the horizontal movement of hydrocarbons from a wellbore where the polymer is injected towards other producing wells in the vicinity. These strategies seek to mobilize hydrocarbons horizontally from the point of injection employing a mixture of water and polymers to the productive region around a producing well. All the prevailing methodologies share the common drawback that nature favors the movement of hydrocarbons vertically rather than horizontally within any given hydrocarbon bearing porous medium.
Because of the natural heterogeneity found in all oil-bearing strata and the fact that an injected fluid will always find its path of least resistance from the point of injection to the point of extraction, all manner of conformance control issues arise when attempting to mobilize hydrocarbons horizontally in a traditional polymer flood. Even in a homogenous reservoir, the displacing polymer will channel through a more viscous oil in a process known as viscous fingering if the viscosity of the injecting polymer fluid is lower than that of the hydrocarbon being mobilized.
Conformance control measures may be implemented to mitigate the phenomenon that the displacing fluid such as a water or polymer/water mixture will not be displaced out radially in a piston-like fashion uniformly displacing the hydrocarbons but instead fingers through the hydrocarbon bearing strata leaving large volumes of oil which remain immobilized and immovable to the producing wellbores. In viscous fingering, the lower viscosity injectant fingers through the more viscous oil, allowing the injectant to reach the producing wellbore first, at which point the less-viscous injectant will be preferentially mobilized in lieu of a more viscous hydrocarbon to the producing wellbore, thus bypassing and leaving behind hydrocarbons which would otherwise be mobilized and produced.
Accordingly, enhanced hydrocarbon recovery methods which facilitate production of hydrocarbon from a hydrocarbon reservoir by beneficially altering the mobility ratio of formation water with respect to hydrocarbon may be desirable for some applications.